西南交通大学学报

Batch Parallel Algorithm of Assignment Problem of Dynamic Transportation Network Flows for System Optimization

DU Wen, LIN Shu-rong, ZΗΟUXian-wei

2001, 14(5): 453-456.

[Abstract](1556)

Abstract:
Intelligent transportation system is a complex integrated system. The study on dynamic transportation network assignment is one of its key techniques and is also the frontier and hot point of transportation science. In this paper, according to a model on the assignment problem of dynamic transportation network flows for system optimization, the solution to assignment problem is obtained based on Kuhn-Tucker conditions of non-linear programming. Because transportation network is a complex large system, the route searching steps for assignment are simplified by processing the transportation network flows using the batch scheduling theory, and a batch parallel scheduling algorithm of assignment problem is designed

On the Connection between Optimal Stock Level and Distribution Structure in Multi-Echelon Storage System

ZHOUHe-fang, LI Zong-ping, DU Wen

2001, 14(5): 457-461.

[Abstract](1360)

Abstract:
In a single-echelon system, the optimal stock level has a square root rule-of-thumb with respect to the furcation degree. For a multi-echelon storage system, the connection between its optimal stock level and distribution structure (echelon number and furcation degree) is obtained by combination of theoretical analysis and numerical calculation, supplying a significant reference for the design of distribution structure.

A Model for Adjustment of Prices of Transportation Enterprises

JU Ting-Ying

2001, 14(5): 462-464.

[Abstract](1419)

Abstract:
How to rationally adjust transportation prices under government’s lenient price control policy is the key problem of raising economic benefits and improving competitive ability for transportation enterprises. In this paper, a price adjustment model is put forward by using economic principles, and an assessment on the factors affecting the transportation prices, such as competitors’ financial power, consumers’bearing capacity to the prices, and so on, is made by adopting specialists and decision-maker’s experience. The magnitude of these factors’effects on transportation prices is given, and the model is revised and proved feasible by an example.

The Air Speed Stability under Wind Shear

WANG Yong-zhong, DU Wen

2001, 14(5): 465-467.

[Abstract](1422)

Abstract:
A mathematical model is established to study the air speed stability. The numerical results of the mathematical model are analyzed, revealing that an air stability parameter, namely the hour constant, is related with the air speed, the wind load, the resistance coefficient and the airplane size. This has some significance for the flight technique under the condition of wind shea.

A Permutation Algorithm for the Linear 0-1 Programming Model

LI Ying-hong

2001, 14(5): 468-471.

[Abstract](1311)

Abstract:
This paper presents a new method, the permutation algorithm, for solving the linear 0-1 programming model. In this algorithm, the unconstrained solutions are permuted in a special order according to the absolute values of variable coefficients of the objective function so as to search the optimum solution in the aggregate of minimums with an accelerated convergence speed.

Chaotic Attractor-Based Time Series Forecasting Method and Its Application

XIANG Xiao-dong, GUO Yao-huang

2001, 14(5): 472-475.

[Abstract](1321)

Abstract:
The phase space reconstruction technique and the computation method of chaotic attractor’s correlation dimensions are introduced. The forecasting principle and the forecasting model based on the peculiarities of chaotic attractors are expounded, deficiencies existing in the present model are disclosed, and modification opinions and a concrete algorithm are put forward. Then, using the time series from Lorenz system as samples for forecasting, the results of three forecasting models are presented for comparison, and some problems remained to be resolved are pointed out.

Nonlinear Programming Algorithms for Nonlinear Least Squares Adjustment by Parameters

FAN Dong-min

2001, 14(5): 476-481.

[Abstract](1485)

Abstract:
Five feasible nonlinear programming algorithms dealing with nonlinear least squares adjustment by parameters are discussed. They are Newton method, speediest descending method, discrete Newton method, quasi-Newton method, and sequential quadratic programming method (SQPM). It is confirmed by analysis, comparison, and computation examples that SQPM is the most powerful tool to solve the problem of nonlinear least squares adjustment by parameters, without exactly computing the approximation of parameters.

The Spatio-Temporal Data Model fo 3-D Spatial Process Simulation

ZHANG Shan-shan, ZHAO Can-hui

2001, 14(5): 481-485.

[Abstract](1385)

Abstract:
Current Geographic Information System ( GIS) software does not support the manipulation of multi-dimensional spatio-temporal data, therefore it is difficult to deal with the geographic phenomena with spatio-temporal multi-dimensions. Spatial process simulation is the main way to study the geographic phenomena. In this paper, a discussion is conducted about the mathematical model of spatial process simulation, the characteristics of spatial process simulation models, and the shortcomings of the present GIS data models. A method using the sequent snapshot approach and the temporal parametric model to support spatial process simulation is put forward, and a practical example is analyzed with combination of seismic dynamic process simulation.

Internal Force Calculation of Beams with Prestressed Anchor-Rope on Foundation

SONG Cong-jun, ZHOU De-pei, XIAO Shi-guo

2001, 14(5): 486-490.

[Abstract](1603)

Abstract:
The calculation methods of internal forces in beams with prestressed anchor-rope on foundation in high slope project are discussed based on Winkler s hypothesis, and the beam on half- space elastic foundation, respectively. These methods are compared with each other in the internal force calculation of an engineering case. According to the analysis of calculation results, the applicable condition for each calculation method is concluded. In addition, the mode of force acting on beam on foundation is analyzed for the pulling and working periods of anchor-ropes. It is pointed out that the internal forces in either the two periods should be calculated respectively. The rational verification methods are also suggested in this paper.

Test Study on Segmental Model of a PPC Box Girder

LIU Shan-hong, HE Guang-han

2001, 14(5): 491-494.

[Abstract](1474)

Abstract:
The model test of the No. 0 segment of a partially prestressed concrete (PPC) continuous box girder designed for Guangzhou-Zhuhai railway is introduced in this paper. This segmental model is analyzed with three-dimensional finite element. The test and calculation results show that, even under the most unfavored load combination, there is no visible cracks observed, and there are obvious shear-lag effects in the top slab of the box girder. Cracking is most likely to occur at the outside of the top flange. In a word, the bridge is designed with enough safety reserve.

Safety Management of Track Irregularities of 250 km/h High-Speed Railway

CHEN Guo, ZHAI Wan-ming, ZUO Hong-fu

2001, 14(5): 495-499.

[Abstract](1565)

Abstract:
Using the vertical-lateral model of vehicle-track coupling system, which is set up based on the vehicle-track coupling dynamics, and taking the coexistence of manifold wavelengths into account, the management values of various track irregularities in 250 km/h high-speed railway are calculated by simulation. The calculation results are consistent with the management values of the high-speed railway of Japan and Germany on the whole.

Research Review on Rail Corrugation

ZHANG Bo, LIU Qi-yue

2001, 14(5): 500-504.

[Abstract](1317)

Abstract:
Rail corrugation is a complex problem that railway enterprises all over the world are eager to solve. In this paper, researches on rail corrugation in recent years are reviewed, and the status quo in this research field is investigated. In the mean time, current perspectives about the classification, causes and prophylactic measures of rail corrugation are summarized with the emphasis of discussion being focused on the formation mechanism and prophylactic measures. It is reckoned that self-excited vibration, reactive vibration and contact fatigue contribute to the formation and grow of rail corrugation.

Analysis of Partial Coefficients of Single-Track Railway Tunnel Portal Structures

ZHOUJia-mei, YAN Song-hong, WANG Ying-xue

2001, 14(5): 505-508.

[Abstract](1794)

Abstract:
According to the calculation characteristics of railway tunnel portal structure, the limit states design equations of tunnel portal structure reliability are established. Based on the given object reliability indexβnom, the partial coefficients of tunnel portal structure are calculated, and the basic principle and specifics process of the calculation are presented. In addition to that, the influencing factors and probabilistic meanings of the partial coefficients are discussed through a practical example.

A Spatial Time-Varying Coupling Model for Dynamic Analysis of High Speed Railway Subgrade

SU Qian, CAI Ying

2001, 14(5): 509-513.

[Abstract](1374)

Abstract:
According to the working condition of high-speed railway, a spatial time-varying model of subgrade/track/vehicle coupling system is established for dynamic analysis of subgrade. In the spatial model, the railway structure and vehicle are dispersed into different elements, the dynamic equation of the coupling system is founded with the energy theory, and the vibration equation made up of the coupled matrixes of the system is also established. Under the continued harmonic irregularity, dynamic analyses are performed and used as the verification of the model. The dynamic responses such as the acceleration of the car, the dynamic wheel load, the subgrade dynamic stresses, the subgrade dynamic deformation,etc., are analyzed during the running of a vehicle. The results show that the calculation model presented in this paper is rational.

Surface Water Quality Influenced by the Groundwater Drained from Qinling Tunnel

WANG Jian-xiu, YANG Li-zhong, LIU Dan

2001, 14(5): 514-517.

[Abstract](1507)

Abstract:
The groundwater from Qinling tunnel on Xi’an-Ankang railway is drained into two rivers-the south into Taiyu river, and the north into Shibianyu river. In order to evaluate the influence of chemical abnormal quality the drained groundwater, the water quality of the two rivers is observed and tested in three sections respectively for three times between 1998 and 1999. Some evaluation factors of the criteria for drinkable water are adopted to divide the surface water into three levels in quality. Fuzzy comprehensive evaluation method and gray system method are used to comprehensively evaluate the quality of surface water in the three sections. The results show that the water quality in the two rivers are not influenced by the tunnel construction and by the water drained from the tunnel.

Control Factors of Anaerobic Digestion and Effect of pH and Eh

LI Gang, YANG Li-zhong, OU Yang-feng

2001, 14(5): 518-521.

[Abstract](1162)

Abstract:
Anaerobic digestion is one of the key technologies for modern wastewater treatment. In this paper, the control factors of anaerobic digestion are discussed based on the summarization of present research literatures. The mechanism of the effect of pH and Eh on anaerobic digestion is analyzed with microbiology and biochemistry theory. The equation describing the effect of pH variation on Gibbs free energy variationΔGis derived using Nernst equation, and the specific control conditions in engineering are summed up according to the present research achievements.

Global Stability of Delayed Hopfield Neural Network Models

ZHANG Ji-ye, YANG Yi-ren, ZENG Jing

2001, 14(5): 522-525.

[Abstract](1586)

Abstract:
The existence of equilibrium and global stability are analyzed for delayed Hopfield neural network models, which have no the original requirements for monotonicity and differentiability in the activation function. By using M matrix theory, Liapunov functionals are constructed to establish the sufficient conditions for global asymptotic stability, thus the existing relevant results are improved.

Regulating Method and Parameters Design for Preventingthe Loss of Control in Traction Motor Feedback Tests

HUHan-chun

2001, 14(5): 526-529.

[Abstract](1382)

Abstract:
The loss of control of current or voltage in traction motor feedback tests is analyzed based on voltage balance and power balance, and the restrictive conditions of non-loss of control is obtained. Since the loss of control is caused by the difference in magnetic field characteristics of motors, a method by regulating the magnetic field is put forward to eliminate the phenomenon of loss of control. The magnetic field regulating device and technical parameters are designed to meet the regulating requirements for all the motor tests.

A Study on Contact Strength of Helical Gears

HU Song, WEN Ze-feng, JINXue-song

2001, 14(5): 530-535.

[Abstract](1326)

Abstract:
The surface equations of meshing gears and the curve equation of the meshing line are established. With several mathematic software and CAD software as assistance tool and using the theory of three-dimensional elastic bodies in non-Hertz rolling contact, the contact stresses at any point of the meshing line are analyzed and the effects of various meshing parameters on the contact strength are summarized. This supplies a new theory for the strength design of helical drive gears.

Some Properties of Filters in Lattice Implication Algebras

WANG Xue-fang, XU Yang, SONG Zhen-ming

2001, 14(5): 536-539.

[Abstract](1242)

Abstract:
Several equivalent conditions for filters are given, and the definition of obstinate filters is introduced. Obstinate filters, maximal implicative filters and maximal positive implicative filters are proved equivalent to each other. It is also concluded that ultrafilters are obstinate filters and obstinate filters are prime filters. An equivalent condition for the obstinate filterLis provided through implication homomorphism, that is, for arbitrary lattice implication algebraL′,there always exists an implication homomorphism fromLtoL′,such that this filter is a dual kernel of this homomorphism.

Reconstruction of Wire-frame Model from Orthographic Views

ZHANG Ai-jun, ZHU Chang-qian

2001, 14(5): 540-544.

[Abstract](1413)

Abstract:
A straightforward approach that automatically reconstructs a wire-frame model from three orthographic views is described in this paper. Firstly, all candidate 3-D vertices are generated from 2-D points in each of three orthographic views. Next, all possible connecting relationships between candidate 3-D vertices are established directly according to connecting relationships between 2-D points in each view, based on the properties of orthographic projection geometry. Then, redundant elements are detected and eliminated on the basis of the properties of regular shape in solid modeling system. Finally, each pair of 3-D vertices with connecting relationship is connected to form a wire- frame model.

The Learning of BP Neural Network Based on Evolutionary Programming

YE Li-sheng, HE Feng-dao

2001, 14(5): 545-548.

[Abstract](1704)

Abstract:
The shortcomings of the traditional methods are point out through the analysis of BP algorithm and genetic algorithm which are commonly applied to BP neural networks. A modified evolutionary programming is proposed to optimize the weight of BP neural network. The simulating results for XOR problem and four-parity problem are given through comparison among BP algorithm, traditional evolutionary algorithm and the proposed modified evolutionary algorithm. The result indicates that the modified evolutionary algorithm proposed in this paper is superior to other two algorithms.

On Secondly Extended Complex-Rotary Codes and Their Dual Codes

JI Qing-bing, HUANG Guang-xin

2001, 14(5): 549-552.

[Abstract](1343)

Abstract:
In this paper, the concepts of secondly extended complex-rotary codes and their dual codes are proposed on the basis of extended complex-rotary codes. Their characters are discussed preliminarily, and the method for their construction and their principle parameters are presented. By comparing the proposed codes with extended complex-rotary codes and their dual codes, it is shown that they are error controlling codes, the correction capacity of which is powerful and the code rate of which is high.

Model Reference Adaptive Control Based on BP Neural Networks

SHEN Ying, ZHANG Cui-fang

2001, 14(5): 553-556.

[Abstract](1696)

Abstract:
A scheme of model reference adaptive control based on BP neural network is presented in this paper. Two BP neural networks are used to identify and control unknown plants. Since a BP neural network has the properties of forward propagation of message and backward propagation of errors, the parameters of a network can be modified to get proper values. The BP identifier is also used as a channel for error propagation. Simulation results show the effectiveness of the proposed scheme.

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2001 Vol. 14, No. 5